System for nickel-free zinc phosphate pretreatment

ABSTRACT

Disclosed is a substrate pretreatment system, comprising (a) an activating rinse for treating at least a portion of a substrate comprising a dispersion of metal phosphate particles having a D 90  particle size of no greater than 10 μm, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof; and (b) a pretreatment composition for treating at least a portion of the substrate treated with the activating rinse, comprising zinc ions and phosphate ions, wherein the pretreatment composition is substantially free of nickel. Methods of treating a substrate with the substrate pretreatment system also are disclosed. Substrates treated with the substrate pretreatment system also are disclosed.

FIELD OF THE INVENTION

A system for pretreating a substrate with a nickel-free zinc phosphatepretreatment composition is disclosed.

BACKGROUND

Phosphate conversion coatings are well known for treating metalsurfaces, particularly ferrous, zinc and aluminum metals and theiralloys. When applied, these phosphate coatings form a phosphate layer,primarily of zinc and iron phosphate crystals, which provides corrosionresistance and/or enhances the adhesion of subsequently appliedcoatings.

Prior to application of the phosphate coating, the metal substrate istypically “conditioned” or “activated” by subjecting the surface of themetal substrate to a diluted aqueous dispersion, sometimes referred toas an activating rinse or activator, by introducing or immersing themetal substrate into a tank that contains the activating rinse.“Activation” of the surface of the metal substrate often is achieved dueto the adsorption of colloidal titanium-phosphate particles, which arepresent in the activating rinse, to the metal's surface. These colloidaltitanium-phosphate particles, however, have a tendency to agglomerate inthe activating rinse bath due to dissolved cations that are typicallypresent in the activating rinse conditioner bath.

The phosphate conversion coating is typically applied to a substrate byimmersing the substrate into a heated bath comprising metal phosphateparticles.

Conventional techniques for coating such substrates include techniquesthat involve pretreating the metal substrate with nickel-containingcompositions. The use of such nickel-containing compositions, however,impart environmental concerns.

SUMMARY

Disclosed is a substrate pretreatment system, comprising (a) anactivating rinse for treating at least a portion of a substratecomprising a dispersion of metal phosphate particles having a D₉₀particle size of no greater than 10 μm, wherein the metal phosphatecomprises divalent or trivalent metals or combinations thereof; and (b)a pretreatment composition for treating at least a portion of thesubstrate treated with the activating rinse, comprising zinc ions andphosphate ions, wherein the pretreatment composition is substantiallyfree of nickel.

Also disclosed is a method of treating a substrate with the substratepretreatment system.

Also disclosed is a substrate treated with the substrate pretreatmentsystem.

DETAILED DESCRIPTION

According to the present invention, the substrate pretreatment systemcomprises, or in some instances consists of, or in some instancesconsists essentially of: an activating rinse for treating at least aportion of a substrate comprising a dispersion of metal phosphateparticles having a D₉₀ particle size of no greater than 10 μm, whereinthe metal phosphate comprises divalent or trivalent metals orcombinations thereof; and (b) a pretreatment composition for treating atleast a portion of the substrate treated with the activating rinse,comprising zinc ions and phosphate ions, wherein the pretreatmentcomposition is substantially free of nickel.

As used herein, the phrase “activating rinse” refers to a continuousaqueous medium having dispersed and/or suspended therein metal phosphateparticles that is applied onto at least a portion of a substrate and/orinto which at least a portion of a substrate is immersed to “activate”or “condition” the substrate in order to promote the formation of ametal phosphate coating on at least a portion of the substrate that wastreated with the activating rinse. As used herein, to “activate” or“condition” the substrate surface means to create nucleation sites onthe substrate surface. While not wishing to be bound by theory, it isbelieved that such nucleation sites promote the formation of metalphosphate crystals on the substrate surface when the substrate surfacesubsequently is treated with a metal phosphate pretreatment composition.For example, activation of the substrate surface is believed to createnucleation sites that promote the formation of zinc and zinc/ironphosphate crystals on the substrate surface when the substrate surfaceis pretreated with a zinc phosphate pretreatment composition.

Non-limiting examples of a suitable substrate that can be treated withthe activating rinse include, but are not limited to, a metal and/or ametal alloy substrate. For example, the metal and/or metal alloy cancomprise or be aluminum, steel, or zinc. According to the presentinvention, a steel substrate could include cold rolled steel,electrogalvanized steel, and hot dipped galvanized steel. According tothe present invention, the substrate may comprise a portion of a vehiclesuch as a vehicular body (e.g., without limitation, door, body panel,trunk deck lid, roof panel, hood, and/or roof) and/or a vehicular frame.

As used herein, the term “vehicle” or variations thereof includes, butis not limited to, civilian, commercial, and military land vehicles suchas cars and trucks.

As used herein, the term “dispersion” refers to a two-phase transparent,translucent or opaque system in which metal phosphate particles are inthe dispersed phase and an aqueous medium, which includes water, is inthe continuous phase. An “aqueous medium” is a liquid medium that is 50weight percent or greater of water, with weight percent based onnon-solid content of the activating rinse. The aqueous medium maycomprise 50 weight percent or less of other organic co-solvents, such as10 weight percent or less. According to the present invention, theorganic co-solvents are at least partially miscible with water. In theaqueous medium, water miscible organic solvents may be present, forexample, alcohols with up to about 8 carbon atoms such as methanol,isopropanol, and the like, or glycol ethers such as the monoalkyl ethersof ethylene glycol, diethylene glycol, or propylene glycol, and thelike.

As used herein, the term “pulverized” refers to particles havingvariable aspect ratios, where the term “aspect ratio” refers to theratio of the length to the width of a particle (i.e., the aspect ratiodoes not define a sphere).

According to the present invention, the metal phosphate particles of thedispersion of metal phosphate particles of divalent or trivalent metalsor combinations thereof may have a D₉₀ particle size that is not greaterthan 10 μm, such as not greater than 8 μm, such as not greater than 5μm, such as not greater than 2 μm, such as not greater than 1 μm and insome cases may be at least 0.06 μm, such as at least 0.1 μm, such as atleast 0.2 μm. According to the present invention, the metal phosphateparticles of the dispersion of phosphate particles of divalent ortrivalent metals or combinations thereof may have a D₉₀ particle size of0.06 μm to 8 μm, such as 0.1 μm to 5 μm, such as 0.2 μm to 2 μm.

As used herein, the term “D₉₀” particle size refers to a volume-weightedparticle distribution in which 90% of the particles in the particledistribution have a diameter smaller than the “D₉₀” value. As usedherein, the term “D₁₀” particle size refers to a volume-weightedparticle distribution in which 10% of the particles in the particledistribution have a diameter smaller than the “D₁₀” value. As usedherein, the term “D₅₀” particle size refers to a volume-weightedparticle distribution in which 50% of the particles in the particledistribution have a diameter smaller than the “D50” value.

According to the present invention, particle size may be measured usingan instrument such as a Mastersizer 2000, available from MalvernInstruments, Ltd., of Malvern, Worcestershire, UK, or an equivalentinstrument. The Mastersizer 2000 directs a laser beam (0.633 mmdiameter, 633 nm wavelength) through a dispersion of particles (indistilled, deionized or filtered water to 2-3% obscuration), andmeasures the light scattering of the dispersion (measurement parameters25° C., 2200 RPM, 30 sec premeasurement delay, 10 sec backgroundmeasurement, 10 sec sample measurement). The amount of light scatteredby the dispersion is inversely proportional to the particle size. Aseries of detectors measure the scattered light and the data are thenanalyzed by computer software (Malvern Mastersizer 2000 software,version 5.60) to generate a particle size distribution, from whichparticle size can be routinely determined.

According to the present invention, the sample of dispersion ofparticles optionally may be sonicated prior to analysis for particlesize. According to the present invention, the sonication processcomprises: (1) mixing the dispersion of particles using a Vortex mixer(Fisher Scientific Vortex Genie 2, or equivalent); (2) adding 15 mL ofdistilled deionized, ultra-filtered water to a 20 mL screw-capscintillation vial; (3) adding 4 drops of the dispersion to the vial;(4) mixing the contents of the vial using the Vortex mixer; (5) cappingthe vial and placing it into an ultrasonic water bath (Fisher ScientificModel FS30, or equivalent) for 5 minutes; (6) vortexing the vial again;and (7) adding the sample dropwise to the Mastersizer to reach anobscuration between 2-3 for particle size distribution analysisdescribed above.

According to the present invention, the metal phosphate particles may besubstantially pulverized, such that more than 90% of the metal phosphateparticles in the activating rinse composition are pulverized, such asmore than 91%, such as more than 92%, such as more than 93%, such asmore than 94%, such as more than 95%, such as more than 96%, such asmore than 97%, such as more than 98%, such as more than 99%. Accordingto the present invention, the metal phosphate particles may becompletely pulverized, such that 100% of the particles are pulverized.

According to the present invention, the metal phosphate (as total metalcompound) may be present in the activating rinse in an amount of atleast 50 ppm, based on total weight of the activating rinse, such as atleast 150 ppm, and in some instances may be present in the activatingrinse in an amount of no more than 5000 ppm, based on total weight ofthe activating rinse, such as no more than 1500 ppm. According to thepresent invention, the metal phosphate (as total metal compound) may bepresent in the activating rinse in an amount of 50 ppm to 5,000 ppm oftotal metal phosphate based on the total weight of the activating rinse,such as of 150 ppm to 1,500 ppm.

According to the present invention, the divalent or trivalent metal ofthe metal phosphate may comprise zinc, iron, calcium, manganese,aluminum, nickel, or combinations thereof. If combinations of differentmetal phosphates are employed, they may comprise the same or differentmetals, and may be selected from the particular zinc, iron, calcium,manganese and aluminum phosphates mentioned in the following.

Suitable zinc phosphates useful in the activating rinse bath include,without limitation Zn₃(PO₄)₂, Zn₂Fe(PO₄)₂, Zn₂Ca(PO₄)₂, Zn₂Mn(PO₄)₂, orcombinations thereof.

Suitable iron phosphates useful in the activating rinse bath include,without limitation FePO₄, Fe₃(PO₄)₂,or combinations thereof.

Suitable calcium phosphates useful in the activating rinse bath include,without limitation CaHPO₄, Ca₃(PO₄)₂,or combinations thereof.

Suitable manganese phosphates useful in the activating rinse bathinclude, without limitation Mn₃(PO₄)₂, MnPO₄,or combinations thereof.

Suitable aluminum phosphates useful in the activating rinse bathinclude, without limitation AlPO₄.

According to the present invention, the activating rinse may furthercomprise a dispersant. The dispersant may be ionic or non-ionic.Suitable ionic dispersants useful in the activating rinse may comprisean aromatic organic acid, a phenolic compound, a phenolic resin, orcombinations thereof. Suitable non-ionic dispersants useful in theactivating rinse may include non-ionic polymers, in particular thosecomprised of monomers (or residues thereof) including propylene oxide,ethylene oxide, styrene, a monoacid such as (meth)acrylic acid, a diacidsuch as maleic acid or itaconic acid, an acid anhydride such as acrylicanhydride or maleic anhydride, or combinations thereof. Examples ofsuitable commercially available non-ionic dispersants includeDISPERBYK®-190 available from BYK-Chemie GmbH and ZetaSperse® 3100available from Air Products Chemicals Inc.

According to the present invention, the activating rinse may besubstantially free or completely free of ionic dispersants. As usedherein, an activating rinse is substantially free of ionic dispersantsif ionic dispersants are present in an amount less than 1% by weight,based on the total weight of the activating rinse. As used herein, anactivating rinse is completely free of ionic dispersants if ionicdispersants are not present in the activating rinse, meaning 0% byweight based on the total weight of the activating rinse.

According to the present invention, the activating rinse optionally mayinclude a metal sulfate salt. The metal of the metal sulfate may be thesame as or different from the metal of the metal phosphate particles.According to the present invention, the metal of the metal sulfate saltmay comprise a divalent metal, a trivalent metal or combinationsthereof, such as, for example, nickel, copper, zinc, iron, magnesium,cobalt, aluminum or combinations thereof.

According to the present invention, when present, if at all, the sulfateion of the metal sulfate salt may be present in the activating rinse inan amount of at least 5 ppm based on the total weight of the activatingrinse, such as at least 10 ppm, such as at least 20 ppm, such as atleast 50 ppm, and in some cases, no more than the solubility limit ofthe metal sulfate salt in the activating rinse, such as no more than5,000 ppm, such as no more than 1,000 ppm, such as no more than 500 ppm,such as no more than 250 ppm. According to the present invention, thesulfate ion of the metal sulfate salt may be present in an amount of 5ppm to 5,000 ppm based on a total amount of sulfate in the metal sulfatesalt, such as 10 ppm to 1,000 ppm, such as 20 ppm to 500 ppm, such as 50ppm to 250 ppm. According to the present invention, the activating rinsemay be substantially free, or in some instances, completely free, ofsulfate ions. As used herein with respect to the sulfate ion of a metalsulfate salt, the term “substantially free” means that the sulfate ionis present in the activating rinse in an amount of less than 5 ppm basedon the total weight of the activating rinse. As used herein with respectto the sulfate ion of a metal sulfate salt, the term “completely free”means that the activating rinse does not comprise a sulfate ion (i.e.,there are 0 ppm of sulfate ion (based on the total weight of theactivating rinse) present in the activating rinse).

According to the present invention, the activating rinse may be in theform of a concentrate, wherein the concentrate has a viscositysufficient to prevent the metal phosphate particles and metal sulfatesalt (if present) from settling out. According to the present invention,in use, the concentrated activating rinse may be diluted with waterand/or an organic solvent.

According to the present invention, the activating rinse may be a 1K(“One-Component”, or “One Part”) composition or a multi-componentcomposition, such as, for example, 2K (“Two-Component”, or “Two Part”)compositions. As defined herein, a “1K” composition is a composition inwhich all of the ingredients may be premixed and stored. By contrast, amulti-component composition is one in which at least two of theingredients are stored separately and are mixed together to form thetreatment bath.

According to the present invention, the activating rinse may be a 1Kcomposition, wherein the 1K composition is formed from: a dispersion ofmetal phosphate particles of divalent metals, trivalent metals orcombinations thereof, the metal phosphate particles having a D₉₀particle size that is not greater than 10 μm; a dispersant; and a metalsulfate salt (if present). Optionally, the 1K activating rinse may be aconcentrate that is diluted to form the bath containing the activatingrinse.

According to the present invention, the activating rinse may be a 2Kcomposition wherein a dispersion of metal phosphate particles ofdivalent metals, trivalent metals or combinations thereof, the metalphosphate particles having a D₉₀ particle size that is not greater than10 μm, and a dispersant form a part of a first component. A metalsulfate salt may form a part of a second component. Additionalcomponents comprising any of the optional ingredients described belowalso may be added to the bath containing the activating rinse. Any ofthe components of the activating rinse may be a concentrate that isdiluted to form the bath containing the activating rinse.

According to the present invention, the activating rinse may include awetting agent. According to the present invention, wetting agents may bepresent at amounts of up to 2 percent by weight, such as up to 0.5percent by weight, based on the total weight of the activating rinse. Insome instances, wetting agents may be present in amounts of 0.1 percentby weight to 2 percent by weight, based on total weight of theactivating rinse, such as 0.3 percent by weight to 0.5 percent byweight. As used herein, a “wetting agent” reduces the surface tension atthe interface between the surface of the particles of the dispersedphase and the aqueous medium to allow the aqueous medium to more evenlycontact or “wet” the surface of the particles of the dispersed phase.

According to the present invention, the activating rinse may have a pHof 6 to 12, such as 6.5 to 9, such as 7.5 to 8.5, such as 7 to 8. Analkaline component may be present in the activating rinse in an amountsufficient to adjust the pH of the activating rinse. Suitable alkalinecomponents may include, for example, sodium hydroxide, sodium carbonate,sodium tripolyphosphate, potassium orthophosphate, or combinationsthereof.

According to the present invention, the activating rinse may alsoinclude a biocide. Suitable biocides include, for example, methyl chloroisothiazolinone, methyl isothiazolinone, or combinations thereof. Whenutilized, the biocide may be present in an amount of at least 10 ppmbased on active material in the activating rinse, such as at least 20ppm, such as at least 80 ppm, such as at least 100 ppm, and in someinstances, no more than 140 ppm, such as no more than 120 ppm, such asno more than 40 ppm, such as no more than 30 ppm. According to thepresent invention, the biocide may be present in an amount of 10 ppm to140 ppm based on active material, such as 10 ppm to 40 ppm, such as 20ppm to 30 ppm, such as 80 ppm to 140 ppm, such as 100 ppm to 120 ppm.The skilled artisan will recognize that biocides may be included in theactivating rinse in amounts based on manufacturer instructions.

According to the present invention, the activating rinse may furthercomprise silica. According to the present invention, the silica may be aprecipitated silica, such as a synthetic amorphous precipitated silica.According to the present invention, the silica may be friable undershear. As used herein, “friable under shear” means that particle sizemay be reduced with shear. According to the present invention, thesilica may comprise, for example, Hi-Sil™ EZ 160G silica (commerciallyavailable from PPG Industries, Inc.). According to the presentinvention, if present, the silica may be present in an amount of atleast 50 ppm, based on total weight of the activating rinse, such as atleast 100 ppm, such as at least 150 ppm, and in some instances, no morethan 5000 ppm, based on total weight of the activating rinse, such as nomore than 1000 ppm, such as no more than 500 ppm. According to thepresent invention, the silica may be present in the activating rinse inan amount of 50 ppm to 5,000 ppm based on the total weight of theactivating rinse, such as 100 ppm to 1,000 ppm, such as from 150 ppm to500 ppm.

The activating rinse may optionally further comprise components inaddition to the dispersant (i.e., components different than thedispersant), such as nonionic surfactants and auxiliaries conventionallyused in the art. Such additional optional components include surfactantsthat function as defoamers. Amphoteric and/or nonionic surfactants maybe used. Defoaming surfactants may be present, if at all, in amounts ofat least at least 0.1 percent by weight, based on total weight of theactivating rinse bath, such as at least 0.5 weight percent by weight,and in some instances, may be present in amounts of no more than 1weight percent, such as no more than 0.7 percent by weight, based on thetotal weight of the activating rinse bath. In some instances, defoamingsurfactants may be present, if at all, in amounts of 0.1 weight percentto 1 weight percent, such as 0.5 weight percent to 0.7 percent byweight, based on total weight of the activating rinse bath.

According to the present invention, the activating rinse may furthercomprise a rheology modifier in addition to the dispersant (i.e.,different than the dispersant). The rheology modifier may comprise, forexample, polyurethanes, acrylic polymers, lattices, styrene/butadiene,polyvinylalcohols, clays such as attapulgite, bentonite, and othermontmorillonite, cellulose based materials such as carboxymethylcellulose, methyl cellulose, (hydroxypropyl)methyl cellulose or gelatin,gums such as guar and xanthan, or combinations thereof.

According to the present invention, the activating rinse may besubstantially or, in some cases, completely, free of titanium-phosphateparticles. As used herein, the term “substantially free,” when used inreference to the absence of titanium-phosphate particles in theactivating rinse, means that any titanium-phosphate particles present inthe activating rinse are not purposefully added and are present in atrace amount of less than 5 ppm, based on the total weight of theactivating rinse. As used herein, the term “completely free,” when usedin reference to the absence of titanium-phosphate particles, means thatthere are no titanium-phosphate particles at all.

The activating rinse of the present invention can be prepared fresh withthe above-mentioned ingredients in the concentrations specified or canbe prepared in the form aqueous concentrates in which the concentrationof various ingredients is considerably higher such that the concentratesmay be diluted with aqueous medium such as water or are diluted byfeeding them into an activating bath containing an activating rinse thathas been in use for some time.

According to the present invention, the activating rinse bath maycomprise a chelator. The chelator may comprise, for example,carboxylates such as tartrates, citrates or gluconates, acetate basedcomplexes such as ethylenediaminetetraacetate or nitrilotriacetate,phosphates such as pentasodium triphosphate or tetrapotassiumpyrophosphate, phosphonates, polycarboxylates, the acids, esters, orsalts of any of the aforementioned, or combinations thereof.

The substrate pretreatment system of the present invention alsocomprises a pretreatment composition comprising zinc ions and phosphateions. The pretreatment composition may be substantially free, or in somecases, essentially free, or in some cases, completely free, of nickel.[As used herein, the term “pretreatment composition” refers to acomposition that, upon contact with a substrate, reacts with andchemically alters the substrate surface and binds to it to form aprotective layer and which contains phosphates of zinc, iron, and/orother divalent metals known in the art.] As used herein, the term“substantially free,” when used with respect to the absence of nickel,means nickel, if present at all in the bath containing the pretreatmentcomposition, the pretreatment composition, and/or layers formed from andcomprising same, and, if present at all, only is present in a traceamount of 5 ppm or less, based on a total weight of the composition orlayer(s), as the case may be. As used herein, the term “essentiallyfree,” when used with respect to the absence of nickel, means nickel, ifpresent at all in the bath containing the pretreatment composition, thepretreatment composition, and/or layers formed from and comprising same,and, if present at all, only is present in a trace amount of 1 ppm orless, based on a total weight of the composition or layer(s), as thecase may be. As used herein, the term “completely free,” when used withrespect to the absence of nickel, means nickel, is absent from the bathcontaining the pretreatment composition, the pretreatment composition,and/or layers formed from and comprising same (i.e., the bath containingthe pretreatment composition, the pretreatment composition, and/orlayers formed from and comprising same contain 0 ppm of nickel,excluding nickel derived from drag-in, substrate(s), and/or dissolutionof equipment.

According to the present invention, the zinc ion content of thepretreatment composition may be at least 500 ppm, based on total weightof the pretreatment composition, such as at least 800 ppm, and in someinstances, may be no more than 1500 ppm, based on total weight of thepretreatment composition, such as no more than 1200 ppm. According tothe present invention, the zinc ion content of the aqueous acidiccompositions may be 500 ppm to 1500 ppm, based on total weight of thepretreatment composition, such as at least 800 ppm to 1200 ppm. Thesource of the zinc ion may be conventional zinc ion sources, such aszinc nitrate, zinc oxide, zinc carbonate, zinc metal, and the like.

According to the present invention, the phosphate content of thepretreatment composition may be at least 8000 ppm, based on total weightof the pretreatment composition, such as at least 12000 ppm, and in somecases may be no more than 20000 ppm, based on total weight of thepretreatment composition, such as no more than 14000 ppm. According tothe present invention, the phosphate content of the pretreatmentcomposition may be 8000 ppm to 20000 ppm, based on total weight of thepretreatment composition, such as 12000 ppm to 14000 ppm. The source ofphosphate ion may be phosphoric acid, monosodium phosphate, disodiumphosphate, and the like.

The pretreatment composition of the present invention may have a pH ofat least 2.5, such as at least 3.0, and in some cases, no more than 5.5,such as no more than 3.5. The pretreatment composition may have a pH of2.5 to 5.5, such as 3.0 to 3.5.

According to the present invention, the pretreatment composition mayalso comprise an accelerator. The accelerator may be present in anamount sufficient to accelerate the formation of the zinc phosphatecoating and may be present in the pretreatment composition in an amountof at least 500 ppm, based on total weight of the pretreatmentcomposition, such as at least 1000 ppm, such as at least 2500 ppm, andin some instances may be present in an amount of no more than 20000 ppm,based on total weight of the pretreatment composition, such as no morethan 10000 ppm, such as no more than 5000 ppm. According to the presentinvention, the accelerator may be present in the pretreatmentcomposition in an amount of 500 ppm to 20000 ppm, based on total weightof the pretreatment composition, such as 1000 ppm to 10000 ppm, such as2500 ppm to 5000 ppm. Useful accelerators may include oximes such asacetaldehyde oxime and acetoxime, nitrites such as sodium nitrite andammonium nitrite, peroxides such as hydrogen peroxide, or combinationsthereof.

According to the present invention, the pretreatment composition mayalso comprise fluoride ion, nitrate ion, and various metal ions, such ascobalt ion, calcium ion, magnesium ion, manganese ion, iron ion, copperion, and the like.

Fluoride ion may be present in the pretreatment composition in an amountof at least 100 ppm, based on total weight of the pretreatmentcomposition, such as at least 250 ppm, and in some instances may bepresent in an amount of no more than 2500 ppm, based on total weight ofthe pretreatment composition, such as no more than 1000 ppm, and in somecases may be present in an amount of 100 ppm to 2500 ppm, based on totalweight of the pretreatment composition, such as 250 ppm to 1000 ppm.

According to the present invention, nitrate ion may be present in thepretreatment composition in an amount of at least 1000 ppm, based ontotal weight of the pretreatment composition, such as at least 2000 ppm,and in some instances may be present in an amount of no more than 10000ppm, based on total weight of the pretreatment composition, such as nomore than 5000 ppm, and in some cases may be present in an amount of1000 ppm to 10000 ppm, based on total weight of the pretreatmentcomposition, such as 2000 ppm to 5000 ppm.

According to the present invention, calcium ion may be present in thepretreatment composition in an amount of at least 100 ppm, based ontotal weight of the pretreatment composition, such as at least 500 ppm,and in some cases, no more than 4000 ppm, based on total weight of thepretreatment composition, such as no more than 2500 ppm, and in somecases may be present in an amount of 100 ppm to 4000 ppm, based on totalweight of the pretreatment composition, such as 500 ppm to 2500 ppm.

According to the present invention, manganese ion may be present in thepretreatment composition in an amount of at least 100 ppm, based ontotal weight of the pretreatment composition., such as at least 200 ppm,such as at least 500 ppm, and in some cases no more than 1500 ppm, basedon total weight of the pretreatment composition, such as no more than1000 ppm, such as no more than 800 ppm, and in some cases, in an amountof 100 ppm to 1500 ppm, based on total weight of the pretreatmentcomposition, such as from 200 ppm to 1000 ppm, such as 500 ppm to 800ppm.

According to the present invention, iron ion may be present in thepretreatment composition in an amount of at least 5 ppm, based on totalweight of the pretreatment composition, such as at least 50 ppm, and insome cases, no more than 500 ppm, based on total weight of thepretreatment composition, such as no more than 300 ppm, and in somecases, may be present in the pretreatment composition in an amount of 5ppm to 500 ppm, such as 50 ppm to 300 ppm.

According to the present invention, copper ion may be present in thepretreatment composition in an amount of at least 1 ppm, based on totalweight of the pretreatment composition, such as at least 3 ppm, and insome cases, no more than 30 ppm, based on total weight of thepretreatment composition, such as no more than 15 ppm, and in somecases, may be present in the pretreatment composition in an amount of 1ppm.

The pretreatment composition of the present invention can be preparedfresh with the above mentioned ingredients in the concentrationsspecified or can be prepared in the form of aqueous concentrates inwhich the concentration of the various ingredients is considerablyhigher such that the concentrates may be diluted with aqueous mediumsuch as water or are diluted by feeding them into a zinc phosphatingcomposition which has been in use for some time. Typical concentratesmay contain at least 10,000 ppm zinc ions, based on total weight of thepretreatment composition concentrate, such as at least 12,000 ppm zincions, such as at least 16,000 ppm zinc ions, and in some cases maycontain no more than 100,000 ppm zinc ions, based on total weight of thepretreatment composition concentrate, such as no more than 30,000 ppmzinc ions, such as no more than 20,000 ppm zinc ions, and in some casesmay contain 10,000 ppm to 100,000 ppm zinc ions, based on total weightof the pretreatment composition concentrate, such as 12,000 ppm to30,000 ppm zinc ions, such as from 16,000 ppm to 20,000 ppm zinc ions.

The substrate pretreatment system of the present invention may be usedin a method of treating a metal substrate comprising contacting at leasta portion of a surface of the substrate with the activating rinsecomprising a dispersion of metal phosphate particles having a D90particle size of no greater than 10 μm, wherein the metal phosphatecomprises divalent or trivalent metals or combinations thereof, andsubsequently contacting at least a portion of the surface that has beencontacted with the activating rinse with the pretreatment compositioncomprising zinc ions and phosphate ions, wherein the pretreatmentcomposition is substantially free of nickel.

Optionally, the substrate surface to be treated in accordance with themethods of the present invention may be cleaned to remove grease, dirt,or other extraneous matter and/or rinsed prior to applying theactivating rinse. Cleaning the substrate surface is often done byemploying mild or strong alkaline cleaners, such as are commerciallyavailable and conventionally used in metal pretreatment processes.Examples of alkaline cleaners suitable for use in the present inventioninclude Chemkleen™ 163, Chemkleen™ 177, Chemkleen™ 181ALP, Chemkleen™490MX, and Chemkleen™ 2010LP each of which is commercially availablefrom PPG Industries, Inc.

Following cleaning, the substrate optionally may be rinsed with tapwater, deionized water, and/or an aqueous solution of rinsing agents inorder to remove any residue. The wet substrate surface optionally may bedried, such as air dried, for example, by using an air knife or warm airblower.

According to the present invention, the activating rinse can be appliedto the substrate surface by spray, roll-coating or immersion techniques.The activating rinse may be applied onto the substrate at a temperatureof, for example, 15° C. to 50° C., such as 25° C. to 35° C. for anysuitable period of time, such as at least 1 second, such as at least 10seconds, such as at least 2 minutes, such as at least 5 minutes.

According to the present invention, the method for treating a substratefurther includes contacting at least a portion of the surface that hasbeen contacted with the activating rinse with the pretreatmentcomposition described above to form a phosphate coating on the surfaceof the “activated” substrate. The pretreatment composition may beapplied by spray application or immersion of the activated substrate inan phosphate bath which contains zinc at a temperature typically rangingfrom 20° C. to 75° C. for 1 to 3 minutes. The bath typically may be anacidic phosphate bath and may comprise iron and/or other divalent metalsknown in the art in addition to the zinc ions, as already discussedabove.

After application of the phosphate coating, the substrate may beoptionally post-rinsed with a chromium or non-chromium containingsolution, optionally rinsed with water and/or optionally dried. Paintmay then be applied, if desired, such as, by electrodeposition or byconventional spray or roll coating techniques.

The present invention is also directed to a substrate treated with thepretreatment system that is disclosed herein. The substrate may comprisenucleation sites formed from an activating rinse described above, andmay further comprise a metal phosphate coating formed from a metalphosphate pretreatment composition described above applied over thenucleation sites formed on at least a portion of the substrate by theactivating rinse. The metal phosphate coating may comprise crystalshaving a crystal size of at least 0.4 μm, such as at least 0.5 μm, suchas at least 0.6 μm, such as at least 0.9 μm, and in some cases no largerthan 4 μm, such as no larger than 2.7 μm, such as no larger than 2.5 μm,such as no larger than 2 μm. The metal phosphate coating may comprisecrystals having a crystal size of 0.4 μm to 4 μm, such as 0.5 μm to 2.5μm, such as 0.6 μm to 2 μm.

Crystal size of a phosphate coating may be determined by methods knownto those skilled in the art. For example, a representative area of thepanel (i.e., a coated area of approximately 1.27 cm by 1.27 cm with noobvious coating defects) may be selected and an image of therepresentative area may be acquired an image at either 5,000× or 10,000×magnification using a scanning electron microscope (SEM), such as, forexample, a Tescan Vega 2 SEM. The magnification utilized will bedependent on the crystal size as high magnification (10,000×) will berequired for crystal sizes that are not distinguishable at 5,000×magnification using an SEM. Nine to twelve evenly-spaced crystals, e.g.ten, on each image may be measured using software known to those skilledin the art, such as, for example, ImageJ (version 1.46), and therepresentative crystal sizes may be averaged to determine crystal size.One skilled in the art will recognize that there can be variations inthis procedure that retain the essential elements of microscopic imagingand averaging of representative crystal size.

In an example, the present invention also may be directed to anactivating stage such as those used in an automotive manufacturingfacility. According to the present invention, the activating stagecomprises immersion of the substrate in a bath which contains theactivating rinse of the substrate pretreatment system that is disclosedherein. According to the present invention, the activating rinse iscontained within the immersion tank at a temperature of 15° C. to 50° C.At least a portion of a surface of the substrate is subjected to theactivating rinse by immersing the substrate in the activating rinse forany suitable period of time, e.g. those already described above. Afterbeing immersed in the activating rinse, a portion of the activatedsubstrate then may be subjected to a phosphatizing step by applying ametal phosphate pretreatment composition, e.g. a zinc phosphatepretreatment composition, to the activated substrate. It should benoted, however, that prior to the application of the metal phosphatepretreatment composition to the activated substrate, additionalactivating rinse can be sprayed onto a portion of the activatedsubstrate via a spraying nozzle as the activated substrate is removedfrom the immersion tank. For example, the spraying nozzle could be aspray bank of nozzles which is positioned downstream from the immersiontank. After the activated substrate exits the immersion tank and/orafter additional activating rinse is applied onto the activatedsubstrate, the activated substrate is phosphatized by applying a metalphosphate pretreatment composition to the activated substrate usingtechniques that are known in the art such as a spray and/or an immersiontechnique.

According to the present invention, the activating stage may comprise anumber of spraying nozzles that are used to apply the activating rinsebath onto a least a portion of a substrate. Disposed beneath thespraying nozzles is a spray tank which is adapted to collect theactivating rinse that exits the spraying nozzles and/or any excessactivating rinse that drips off the surface of the activated substrate.The spray tank is connected to the spraying nozzles in a manner thatallows the spraying nozzles to utilize the activating rinse that iscollected in the spray tank thereby recycling the activating rinse bath.After the activating rinse is applied onto at least a portion of thesubstrate, the activated substrate is then phosphatized as described inthe preceding paragraph.

According to the present invention, after the substrate is contactedwith the pretreatment composition, a coating composition comprising afilm-forming resin may be deposited onto at least a portion of thesurface of the substrate that has been contacted with the pretreatmentcomposition. Any suitable technique may be used to deposit such acoating composition onto the substrate, including, for example,brushing, dipping, flow coating, spraying and the like. In someinstances, however, as described in more detail below, such depositingof a coating composition may comprise an electrocoating step wherein anelectrodepositable composition is deposited onto a metal substrate byelectrodeposition. In certain other instances, as described in moredetail below, such depositing of a coating composition comprises apowder coating step. In still other instances, the coating compositionmay be a liquid coating composition.

According to the present invention, the coating composition may comprisea thermosetting film-forming resin or a thermoplastic film-formingresin. As used herein, the term “film-forming resin” refers to resinsthat can form a self-supporting continuous film on at least a horizontalsurface of a substrate upon removal of any diluents or carriers presentin the composition or upon curing at ambient or elevated temperature.Conventional film-forming resins that may be used include, withoutlimitation, those typically used in automotive OEM coating compositions,automotive refinish coating compositions, industrial coatingcompositions, architectural coating compositions, coil coatingcompositions, and aerospace coating compositions, among others. As usedherein, the term “thermosetting” refers to resins that “set”irreversibly upon curing or crosslinking, wherein the polymer chains ofthe polymeric components are joined together by covalent bonds. Thisproperty is usually associated with a cross-linking reaction of thecomposition constituents often induced, for example, by heat orradiation. Curing or crosslinking reactions also may be carried outunder ambient conditions. Once cured or crosslinked, a thermosettingresin will not melt upon the application of heat and is insoluble insolvents. As used herein, the term “thermoplastic” refers to resins thatcomprise polymeric components that are not joined by covalent bonds andthereby can undergo liquid flow upon heating and are soluble insolvents.

As previously indicated, according to the present invention, a coatingcomposition comprising a film-forming resin may be deposited onto thesubstrate by an electrocoating step wherein an electrodepositablecomposition is deposited onto the metal substrate by electrodeposition.In the process of electrodeposition, the metal substrate being treated,serving as an electrode, and an electrically conductive counterelectrode are placed in contact with an ionic, electrodepositablecomposition. Upon passage of an electric current between the electrodeand counter electrode while they are in contact with theelectrodepositable composition, an adherent film of theelectrodepositable composition will deposit in a substantiallycontinuous manner on the metal substrate.

According to the present invention, such electrodeposition may becarried out at a constant voltage in the range of from 1 volt to severalthousand volts, typically between 50 and 500 volts. Current density isusually between 1.0 ampere and 15 amperes per square foot (10.8 to 161.5amperes per square meter) and tends to decrease quickly during theelectrodeposition process, indicating formation of a continuousself-insulating film.

According to the present invention, the electrodepositable coatingcomposition may comprise a resinous phase dispersed in an aqueous mediumwherein the resinous phase comprises: (a) an active hydrogengroup-containing ionic electrodepositable resin, and (b) a curing agenthaving functional groups reactive with the active hydrogen groups of(a).

According to the present invention, the electrodepositable compositionsmay contain for instance, as a main film-forming polymer, an activehydrogen-containing ionic, often cationic, electrodepositable resin. Awide variety of electrodepositable film-forming resins are known and canbe used in the present invention so long as the polymers are “waterdispersible,” i.e., adapted to be solubilized, dispersed or emulsifiedin water. The water dispersible polymer is ionic in nature, that is, thepolymer will contain anionic functional groups to impart a negativecharge or may contain cationic functional groups to impart a positivecharge.

Examples of film-forming resins suitable for use in anionicelectrodepositable coating compositions are base-solubilized, carboxylicacid containing polymers, such as the reaction product or adduct of adrying oil or semi-drying fatty acid ester with a dicarboxylic acid oranhydride; and the reaction product of a fatty acid ester, unsaturatedacid or anhydride and any additional unsaturated modifying materialswhich are further reacted with polyol. Also suitable are the at leastpartially neutralized interpolymers of hydroxy-alkyl esters ofunsaturated carboxylic acids, unsaturated carboxylic acid and at leastone other ethylenically unsaturated monomer. Still another suitableelectrodepositable film-forming resin comprises an alkyd-aminoplastvehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyderesin. Yet another anionic electrodepositable resin compositioncomprises mixed esters of a resinous polyol, such as is described inU.S. Pat. No. 3,749,657 at col. 9, lines 1 to 75 and col. 10, lines 1 to13, the cited portion of which being incorporated herein by reference.Other acid functional polymers can also be used, such as phosphatizedpolyepoxide or phosphatized acrylic polymers as are known to thoseskilled in the art.

As aforementioned, it is often desirable that the activehydrogen-containing ionic electrodepositable resin (a) is cationic andcapable of deposition on a cathode. Examples of such cationicfilm-forming resins include amine salt group-containing resins, such asthe acid-solubilized reaction products of polyepoxides and primary orsecondary amines, such as those described in U.S. Pat. Nos. 3,663,389;3,984,299; 3,947,338; and 3,947,339. Often, these amine saltgroup-containing resins are used in combination with a blockedisocyanate curing agent. The isocyanate can be fully blocked, asdescribed in U.S. Pat. No. 3,984,299, or the isocyanate can be partiallyblocked and reacted with the resin backbone, such as is described inU.S. Pat. No. 3,947,338. Also, one-component compositions as describedin U.S. Pat. No. 4,134,866 and DE-OS No. 2,707,405 can be used as thefilm-forming resin. Besides the epoxy-amine reaction products,film-forming resins can also be selected from cationic acrylic resins,such as those described in U.S. Pat. Nos. 3,455,806 and 3,928,157.

Besides amine salt group-containing resins, quaternary ammonium saltgroup-containing resins can also be employed, such as those formed fromreacting an organic polyepoxide with a tertiary amine salt as describedin U.S. Pat. Nos. 3,962,165; 3,975,346; and 4,001,101. Examples of othercationic resins are ternary sulfonium salt group-containing resins andquaternary phosphonium salt-group containing resins, such as thosedescribed in U.S. Pat. Nos. 3,793,278 and 3,984,922, respectively. Also,film-forming resins which cure via transesterification, such asdescribed in European Application No. 12463 can be used. Further,cationic compositions prepared from Mannich bases, such as described inU.S. Pat. No. 4,134,932, can be used.

According to the present invention, the resins present in theelectrodepositable composition are positively charged resins whichcontain primary and/or secondary amine groups, such as described in U.S.Pat. Nos. 3,663,389; 3,947,339; and 4,116,900. In U.S. Pat. No.3,947,339, a polyketimine derivative of a polyamine, such asdiethylenetriamine or triethylenetetraamine, is reacted with apolyepoxide. When the reaction product is neutralized with acid anddispersed in water, free primary amine groups are generated. Also,equivalent products are formed when polyepoxide is reacted with excesspolyamines, such as diethylenetriamine and triethylenetetraamine, andthe excess polyamine vacuum stripped from the reaction mixture, asdescribed in U.S. Pat. Nos. 3,663,389 and 4,116,900.

According to the present invention, the active hydrogen-containing ionicelectrodepositable resin may be present in the electrodepositablecomposition in an amount of 1 to 60 percent by weight, such as 5 to 25percent by weight, based on total weight of the electrodeposition bath.

As indicated, the resinous phase of the electrodepositable compositionoften further comprises a curing agent adapted to react with the activehydrogen groups of the ionic electrodepositable resin. For example, bothblocked organic polyisocyanate and aminoplast curing agents are suitablefor use in the present invention.

Aminoplast resins may be used as the curing agent for anionicelectrodeposition, are the condensation products of amines or amideswith aldehydes. Examples of suitable amines or amides are melamine,benzoguanamine, urea and similar compounds. Generally, the aldehydeemployed is formaldehyde, although products can be made from otheraldehydes, such as acetaldehyde and furfural. The condensation productscontain methylol groups or similar alkylol groups depending on theparticular aldehyde employed. Often, these methylol groups areetherified by reaction with an alcohol, such as a monohydric alcoholcontaining from 1 to 4 carbon atoms, such as methanol, ethanol,isopropanol, and n-butanol. Aminoplast resins are commercially availablefrom American Cyanamid Co. under the trademark CYMEL and from MonsantoChemical Co. under the trademark RESIMENE.

The aminoplast curing agents are often utilized in conjunction with theactive hydrogen containing anionic electrodepositable resin in amountsranging from 5 percent to 60 percent by weight, such as from 20 percentto 40 percent by weight, the percentages based on the total weight ofthe resin solids in the electrodepositable composition. As indicated,blocked organic polyisocyanates are often used as the curing agent incathodic electrodeposition compositions. The polyisocyanates can befully blocked as described in U.S. Pat. No. 3,984,299 at col. 1, lines 1to 68, col. 2, and col. 3, lines 1 to 15, or partially blocked andreacted with the polymer backbone as described in U.S. Pat. No.3,947,338 at col. 2, lines 65 to 68, col. 3, and col. 4 lines 1 to 30,the cited portions of which being incorporated herein by reference. By“blocked” is meant that the isocyanate groups have been reacted with acompound so that the resultant blocked isocyanate group is stable toactive hydrogens at ambient temperature but reactive with activehydrogens in the film forming polymer at elevated temperatures usuallybetween 90° C. and 200° C.

Suitable polyisocyanates include aromatic and aliphatic polyisocyanates,including cycloaliphatic polyisocyanates and representative examplesinclude diphenylmethane-4,4′-diisocyanate (MDI), 2,4- or 2,6-toluenediisocyanate (TDI), including mixtures thereof, p-phenylenediisocyanate, tetramethylene and hexamethylene diisocyanates,dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, mixturesof phenylmethane-4,4′-diisocyanate and polymethylenepolyphenylisocyanate. Higher polyisocyanates, such as triisocyanates canbe used. An example would includetriphenylmethane-4,4′,4″-triisocyanate. Isocyanate prepolymers withpolyols such as neopentyl glycol and trimethylolpropane and withpolymeric polyols such as polycaprolactone diols and triols (NCO/OHequivalent ratio greater than 1) can also be used.

The polyisocyanate curing agents are typically utilized in conjunctionwith the active hydrogen containing cationic electrodepositable resin inamounts ranging from 5 percent to 60 percent by weight, such as from 20percent to 50 percent by weight, the percentages based on the totalweight of the resin solids of the electrodepositable composition.

The electrodepositable coating compositions described herein may inparticular be in the form of an aqueous dispersion. The average particlesize of the resinous phase is generally less than 1.0 micron and usuallyless than 0.5 microns, often less than 0.15 micron.

The concentration of the resinous phase in the aqueous medium is oftenat least 1 percent by weight, such as from 2 to 60 percent by weight,based on total weight of the aqueous dispersion. When such coatingcompositions are in the form of resin concentrates, they generally havea resin solids content of 20 to 60 percent by weight based on weight ofthe aqueous dispersion.

The electrodepositable coating compositions described herein are oftensupplied as two components: (1) a clear resin feed, which includesgenerally the active hydrogen-containing ionic electrodepositable resin,i.e., the main film-forming polymer, the curing agent, and anyadditional water-dispersible, non-pigmented components; and (2) apigment paste, which generally includes one or more colorants (describedbelow), a water-dispersible grind resin which can be the same ordifferent from the main-film forming polymer, and, optionally, additivessuch as wetting or dispersing aids. Electrodeposition bath components(1) and (2) are dispersed in an aqueous medium which comprises waterand, usually, coalescing solvents.

As aforementioned, besides water, the aqueous medium may contain acoalescing solvent. Useful coalescing solvents are often hydrocarbons,alcohols, esters, ethers and ketones. Coalescing solvents that may beused may be alcohols, polyols and ketones. Specific coalescing solventsinclude isopropanol, butanol, 2-ethylhexanol, isophorone,2-methoxypentanone, ethylene and propylene glycol and the monoethylmonobutyl and monohexyl ethers of ethylene glycol. The amount ofcoalescing solvent is generally between 0.01 and 25 percent, such asfrom 0.05 to 5 percent by weight based on total weight of the aqueousmedium.

After deposition of the electrodepositable coating composition, thecoating is often heated to cure the deposited composition. The heatingor curing operation is often carried out at a temperature in the rangeof from 120 to 250° C., such as from 120 to 190° C., for a period oftime ranging from 10 to 60 minutes. According to the invention, thethickness of the resultant film is from 10 to 50 microns.

Alternatively, as mentioned above, according to the present invention,after the substrate has been contacted with the pretreatmentcomposition, a powder coating composition may then be deposited onto atleast a portion of the surface of the substrate that has been contactedwith the pretreatment composition. As used herein, “powder coatingcomposition” refers to a coating composition which is completely free ofwater and/or solvent. Accordingly, the powder coating compositiondisclosed herein is not synonymous to waterborne and/or solvent-bornecoating compositions known in the art.

According to the present invention, the powder coating compositioncomprises (a) a film forming polymer having a reactive functional group;and (b) a curing agent that is reactive with the functional group.Examples of powder coating compositions that may be used in the presentinvention include the polyester-based ENVIROCRON line of powder coatingcompositions (commercially available from PPG Industries, Inc.) orepoxy-polyester hybrid powder coating compositions. Alternative examplesof powder coating compositions that may be used in the present inventioninclude low temperature cure thermosetting powder coating compositionscomprising (a) at least one tertiary aminourea compound, at least onetertiary aminourethane compound, or mixtures thereof, and (b) at leastone film-forming epoxy-containing resin and/or at least onesiloxane-containing resin (such as those described in U.S. Pat. No.7,470,752, assigned to PPG Industries, Inc. and incorporated herein byreference); curable powder coating compositions generally comprising (a)at least one tertiary aminourea compound, at least one tertiaryaminourethane compound, or mixtures thereof, and (b) at least onefilm-forming epoxy-containing resin and/or at least onesiloxane-containing resin (such as those described in U.S. Pat. No.7,432,333, assigned to PPG Industries, Inc. and incorporated herein byreference); and those comprising a solid particulate mixture of areactive group-containing polymer having a T_(g) of at least 30° C.(such as those described in U.S. Pat. No. 6,797,387, assigned to PPGIndustries, Inc. and incorporated herein by reference).

Suitable film forming polymers that may be used in the powder coatingcomposition of the present invention comprise a (poly)ester (e.g.,polyester triglycidyl isocyanurate), a (poly)urethane, an isocyanurate,a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a(poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride,(poly)olefin, (poly)vinylidene fluoride, or combinations thereof.

According to the present invention, the reactive functional group of thefilm forming polymer of the powder coating composition compriseshydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate),primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl,unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide,epoxy, or combinations thereof.

Suitable curing agents (crosslinking agents) that may be used in thepowder coating composition of present invention comprise an aminoplastresin, a polyisocyanate, a blocked polyisocyanate, a polyepoxide, apolyacid, a polyol, or combinations thereof.

After deposition of the powder coating composition, the coating is oftenheated to cure the deposited composition. The heating or curingoperation is often carried out at a temperature in the range of from150° C. to 200° C., such as from 170° C. to 190° C., for a period oftime ranging from 10 to 20 minutes. According to the invention, thethickness of the resultant film is from 50 microns to 125 microns.

As mentioned above, the coating composition may be a liquid coatingcomposition. As used herein, “liquid coating composition” refers to acoating composition which contains a portion of water and/or solvent.Accordingly, the liquid coating composition disclosed herein issynonymous to waterborne and/or solventborne coating compositions knownin the art.

As mentioned above, according to the present invention, the coatingcomposition may be a liquid coating composition. As used herein, “liquidcoating composition” refers to a coating composition which contains aportion of water and/or solvent. Accordingly, the liquid coatingcomposition disclosed herein is synonymous to waterborne and/orsolventborne coating compositions known in the art.

According to the present invention, the liquid coating composition maycomprise, for example, (a) a film forming polymer having a reactivefunctional group; and (b) a curing agent that is reactive with thefunctional group. In other examples, the liquid coating may contain afilm forming polymer that may react with oxygen in the air or coalesceinto a film with the evaporation of water and/or solvents. These filmforming mechanisms may require or be accelerated by the application ofheat or some type of radiation such as Ultraviolet or Infrared. Examplesof liquid coating compositions that may be used in the present inventioninclude the SPECTRACRON® line of solvent based coating compositions, theAQUACRON® line of water based coating compositions, and the RAYCRON®line of UV cured coatings (all commercially available from PPGIndustries, Inc.).

Suitable film forming polymers that may be used in the liquid coatingcomposition of the present invention may comprise a (poly)ester, analkyd, a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy,an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine,a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidenefluoride, (poly)siloxane, or combinations thereof.

According to the present invention, the reactive functional group of thefilm forming polymer of the liquid coating composition may comprisehydroxyl, carboxyl, isocyanate (including blocked (poly)isocyanate),primary amine, secondary amine, amide, carbamate, urea, urethane, vinyl,unsaturated ester, maleimide, fumarate, anhydride, hydroxyl alkylamide,epoxy, or combinations thereof.

Suitable curing agents (crosslinking agents) that may be used in theliquid coating composition of the present invention may comprise anaminoplast resin, a polyisocyanate, a blocked polyisocyanate, apolyepoxide, a polyacid, a polyol, or combinations thereof.

In addition, a colorant and, if desired, various additives such assurfactants, wetting agents or catalyst can be included in the coatingcomposition (electrodepositable, powder, or liquid). As used herein, theterm “colorant” means any substance that imparts color and/or otheropacity and/or other visual effect to the composition. The colorant canbe added to the composition in any suitable form, such as discreteparticles, dispersions, solutions and/or flakes. A single colorant or amixture of two or more colorants can be used.

Example colorants include pigments, dyes and tints, such as those usedin the paint industry and/or listed in the Dry Color ManufacturersAssociation (DCMA), as well as special effect compositions. A colorantmay include, for example, a finely divided solid powder that isinsoluble but wettable under the conditions of use. A colorant can beorganic or inorganic and can be agglomerated or non-agglomerated.Colorants can be incorporated by use of a grind vehicle, such as anacrylic grind vehicle, the use of which will be familiar to one skilledin the art.

Example pigments and/or pigment compositions include, but are notlimited to, carbazole dioxazine crude pigment, azo, monoazo, disazo,naphthol AS, salt type (lakes), benzimidazolone, condensation, metalcomplex, isoindolinone, isoindoline and polycyclic phthalocyanine,quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo,anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone,anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments,diketo pyrrolo pyrrole red (“DPPBO red”), titanium dioxide, carbon blackand mixtures thereof. The terms “pigment” and “colored filler” can beused interchangeably.

Example dyes include, but are not limited to, those that are solventand/or aqueous based such as phthalo green or blue, iron oxide, bismuthvanadate, anthraquinone, perylene, aluminum and quinacridone.

Example tints include, but are not limited to, pigments dispersed inwater-based or water miscible carriers such as AQUA-CHEM 896commercially available from Degussa, Inc., CHARISMA COLORANTS andMAXITONER INDUSTRIAL COLORANTS commercially available from AccurateDispersions division of Eastman Chemical, Inc.

As noted above, the colorant can be in the form of a dispersionincluding, but not limited to, a nanoparticle dispersion. Nanoparticledispersions can include one or more highly dispersed nanoparticlecolorants and/or colorant particles that produce a desired visible colorand/or opacity and/or visual effect. Nanoparticle dispersions caninclude colorants such as pigments or dyes having a particle size ofless than 150 nm, such as less than 70 nm, or less than 30 nm.Nanoparticles can be produced by milling stock organic or inorganicpigments with grinding media having a particle size of less than 0.5 mm.Example nanoparticle dispersions and methods for making them areidentified in U.S. Pat. No. 6,875,800 B2, which is incorporated hereinby reference. Nanoparticle dispersions can also be produced bycrystallization, precipitation, gas phase condensation, and chemicalattrition (i.e., partial dissolution). In order to minimizere-agglomeration of nanoparticles within the coating, a dispersion ofresin-coated nanoparticles can be used. As used herein, a “dispersion ofresin-coated nanoparticles” refers to a continuous phase in which isdispersed discreet “composite microparticles” that comprise ananoparticle and a resin coating on the nanoparticle. Exampledispersions of resin-coated nanoparticles and methods for making themare identified in United States Patent Application Publication2005-0287348 A1, filed Jun. 24, 2004, U.S. Provisional Application No.60/482,167 filed Jun. 24, 2003, and U.S. patent application Ser. No.11/337,062, filed Jan. 20, 2006, which is also incorporated herein byreference.

Example special effect compositions that may be used include pigmentsand/or compositions that produce one or more appearance effects such asreflectance, pearlescence, metallic sheen, phosphorescence,fluorescence, photochromism, photosensitivity, thermochromism,goniochromism and/or color-change. Additional special effectcompositions can provide other perceptible properties, such as opacityor texture. According to the invention, special effect compositions canproduce a color shift, such that the color of the coating changes whenthe coating is viewed at different angles. Example color effectcompositions are identified in U.S. Pat. No. 6,894,086, incorporatedherein by reference. Additional color effect compositions can includetransparent coated mica and/or synthetic mica, coated silica, coatedalumina, a transparent liquid crystal pigment, a liquid crystal coating,and/or any composition wherein interference results from a refractiveindex differential within the material and not because of the refractiveindex differential between the surface of the material and the air.

According to the invention, a photosensitive composition and/orphotochromic composition, which reversibly alters its color when exposedto one or more light sources, can be used. Photochromic and/orphotosensitive compositions can be activated by exposure to radiation ofa specified wavelength. When the composition becomes excited, themolecular structure is changed and the altered structure exhibits a newcolor that is different from the original color of the composition. Whenthe exposure to radiation is removed, the photochromic and/orphotosensitive composition can return to a state of rest, in which theoriginal color of the composition returns. According to the invention,the photochromic and/or photosensitive composition can be colorless in anon-excited state and exhibit a color in an excited state. Fullcolor-change can appear within milliseconds to several minutes, such asfrom 20 seconds to 60 seconds. Example photochromic and/orphotosensitive compositions include photochromic dyes.

According to the invention, the photosensitive composition and/orphotochromic composition can be associated with and/or at leastpartially bound to, such as by covalent bonding, a polymer and/orpolymeric materials of a polymerizable component. In contrast to somecoatings in which the photosensitive composition may migrate out of thecoating and crystallize into the substrate, the photosensitivecomposition and/or photochromic composition associated with and/or atleast partially bound to a polymer and/or polymerizable component inaccording to the invention, have minimal migration out of the coating.Example photosensitive compositions and/or photochromic compositions andmethods for making them are identified in U.S. application Ser. No.10/892,919 filed Jul. 16, 2004, incorporated herein by reference.

In general, the colorant can be present in the coating composition inany amount sufficient to impart the desired visual and/or color effect.The colorant may comprise from 1 to 65 weight percent, such as from 3 to40 weight percent or 5 to 35 weight percent, with weight percent basedon the total weight of the composition.

According to the present invention, it has been unexpectedly andsurprisingly discovered that the application of the activating rinsedisclosed herein to a surface of the metal substrate prior toapplication of the metal phosphate pretreatment composition enables thebath containing the metal phosphate pretreatment composition to bemaintained (and therefore the metal phosphate pretreatment compositionto be applied) at a lower temperature than methods employingconventional activating rinses, such as Jernstedt type activators orother zinc phosphate activating rinses comprising metal phosphateparticles having a D₉₀ particle size of greater than 10 μm. As G. W.Jernstedt discovered the beneficial effects of activating metal surfacesby treating them with a solution containing titanium together withsodium phosphate prior to zinc phosphating, titanium containingactivating compositions are now generally referred to as “Jernstedt typeactivators”. For example, according to the present invention, thephosphate bath containing the nickel-free metal phosphate pretreatmentcomposition may be at a temperature of no greater than 60° C., such asno greater than 50° C., such as no greater than 40° C., such as nogreater than 30° C., such as no greater than 25° C. According to thepresent invention, the temperature of the bath containing thenickel-free metal phosphate pretreatment composition may range from 20°C. to 60° C., such as from 25° C. to 50° C., such as from 30° C. to 40°C. According to the present invention, application of the activatingrinse disclosed herein to a surface of the metal substrate prior toapplication of the nickel-free metal phosphate pretreatment compositionmay enable the bath containing the nickel-free metal phosphatepretreatment composition to be maintained at room temperature (20° C.).

It also has been unexpectedly and surprisingly discovered thatapplication of the activating rinse disclosed herein to a surface of themetal substrate prior to application of the nickel-free metal phosphatepretreatment composition results in a metal phosphate coating formed onthe substrate surface that has a lower coating weight, smaller phosphatecrystal size, increased coating coverage, and improved adhesionperformance compared to metal phosphate coatings formed on substratesurfaces treated with conventional activating rinses, such as Jernstedttype activators or activating rinses comprising metal phosphateparticles having a D₉₀ particle size of greater than 10 μm. While notwishing to be bound by theory, it is believed that smaller phosphatecrystal sizes are the result of faster reaction of the activating rinsewith the substrate surface and impart more complete coverage of thesubstrate surface with nucleation sites, which leads to more completecoverage of the substrate surface with the subsequently appliednickel-free metal phosphate-containing pretreatment composition.

As used herein, unless indicated otherwise, a plural term can encompassits singular counterpart and vice versa, unless indicated otherwise. Forexample, although reference is made herein to “a” metal sulfate salt and“a” dispersant, a combination (i.e., a plurality) of these componentscan be used. In addition, in this application, the use of “or” means“and/or” unless specifically stated otherwise, even though “and/or” maybe explicitly used in certain instances.

As used herein, “including,” “containing” and like terms are understoodin the context of this application to be synonymous with “comprising”and are therefore open-ended and do not exclude the presence ofadditional undescribed or unrecited elements, materials, ingredients ormethod steps. As used herein, “consisting of” is understood in thecontext of this application to exclude the presence of any unspecifiedelement, ingredient or method step. As used herein, “consistingessentially of” is understood in the context of this application toinclude the specified elements, materials, ingredients, solvents, ormethod steps, where applicable, while other non-specified materials arenot purposefully added to the composition and are only present asimpurities in a combined amount of less than 5% by weight based on atotal weight of the composition.

As used herein, unless indicated otherwise, the term “substantiallyfree” means that a particular material is not purposefully added to theactivating rinse, and is only present as an impurity in a trace amountof less than 1% by weight based on a total weight of the activatingrinse. As used herein, unless indicated otherwise, the term “completelyfree” means that an activating rinse does not comprise a particularmaterial, i.e., the activating rinse comprises 0% by weight of suchmaterial.

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers such as those expressing values, amounts,percentages, ranges, subranges and fractions may be read as if prefacedby the word “about,” even if the term does not expressly appear.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired properties to beobtained by the present invention. Notwithstanding that the numericalranges and parameters setting forth the broad scope of the invention areapproximations, the numerical values set forth in the specific examplesare reported as precisely as possible. Any numerical value, however,inherently contains certain errors necessarily resulting from thestandard variation found in their respective testing measurements. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques. Where a closed or open-ended numerical range is describedherein, all numbers, values, amounts, percentages, subranges andfractions within or encompassed by the numerical range are to beconsidered as being specifically included in and belonging to theoriginal disclosure of this application as if these numbers, values,amounts, percentages, subranges and fractions had been explicitlywritten out in their entirety.

Illustrating the invention are the following examples that are not to beconsidered as limiting the invention to their details. All parts andpercentages in the examples, as well as throughout the specification,are by weight unless otherwise indicated.

EXAMPLES Activating Rinse Compositions

The following activating rinse compositions were prepared as follows:

RC: RC (a Jernstedt-type activating rinse concentrate commerciallyavailable from PPG Industries, Inc., also known as VERSABOND® RC) wasdiluted in deionized (DI) water to a concentration of 1 g concentrate/LDI water to prepare a bath containing the activating rinse composition.

RC30: 1.1 grams of RC30 (a zinc phosphate-based activating rinseconcentrate with an average zinc phosphate particle size of about 1 μmand a D₉₀ of 1-3 μm, commercially available from PPG Industries, Inc.,also known as VERSABOND® 30) was added to 1 liter of deionized water toproduce a dispersion of zinc phosphate with a concentration of 1.1 g/L.

Micromedia-milled zinc phosphate-based activator (MMM):Micromedia-milled zinc phosphate (MMM) is a zinc phosphate-basedactivating rinse that was prepared as follows: 1288.4 grams of zincphosphate pigment was sifted into a pre-blended mixture of 724 gramsdeionized water, 787.7 grams of dispersant (Disperbyk-190, commerciallyavailable from BYK-Chemie GmbH), and 25.6 grams of defoamer (BYK-011,commercially available from BYK-Chemie GmbH) and mixed for 30 minutesusing a Fawcett Air Mixer, model LS-103A with a type 1 angledtooth/Cowles style blade. This mixture was then milled in recirculationmode through an Eiger Mini 250 horizontal media mill (from EMImills)containing 1.2-1.7 mm zirconium oxide media for 8.1 minutes of residencetime. To 1695.7 grams of this preliminary dispersion was added 150.3grams of deionized water. This material was then milled in recirculationmode through the above-described Eiger mill, except that 0.3 mmzirconium oxide media was used. The mixture was milled for an additional40.1 minutes residence time. An additional 718 grams of deionized water,as well as 158.3 grams Disperbyk-190 and 2 grams of Byk-011, were addedthroughout the milling process. Several interim process samples weretaken throughout the milling, such that a final yield of 1657.3 gramswas obtained. This material had a concentration of 27% by weight of zincphosphate. 1.85 grams of the above dispersion of zinc phosphate wasmixed per liter of deionized water, to give an activator bath with azinc phosphate concentration of 0.5 grams per liter.

In the Examples that follow, some activating baths included metalsulfates of the type and in the amounts indicated in Tables 1 and 2,below.

Nickel-Free Phosphate Pretreatment Composition

A nickel-free zinc phosphate pretreatment concentrate was prepared bycarefully combining the following materials and mixing thoroughly untilclear:

Chemical Quantity Phosphoric Acid (85%), available from Fisher 595.6grams Chemical Nitric Acid (Reagent Grade), available from 28.7 gramsFisher Chemical Zinc Oxide, available from Umicore Zinc 62.25 gramsChemicals Manganese Oxide, available from Sigma-Aldrich 32.7 gramsCorporation Acetaldoxime (50% wt), available from Sigma- 1.95 gramsAldrich Corporation Ferrous Sulfate, available from Sigma-Aldrich 3.75grams Corporation Dowfax 2A1 Surfactant, available from The Dow 1.05grams Chemical Co. 50% Sodium Hydroxide Solution, available from 72grams The Dow Chemical Co. Deionized Water 702 grams

Five gallons of a nickel-free zinc phosphate pretreatment bath was thenprepared by adding the following materials in order into deionizedwater:

Chemical Quantity Nickel-free zinc phosphate concentrate 756 gramsChemfos ® 700 F* (partially neutralized 56.75 grams fluosilicic acid)Chemfos ® 700 F/F* (a solution of ammonium 122.85 grams bifluoride)Chemfos ® AZN* (zinc nitrate solution) 15.4 grams Acetaldoxime (50% w/w)8.505 grams Hydrogen Peroxide (30% w/w), available from 1.7 grams AcrosOrganics Buffer M* (a solution of strong base) 321.3 grams *Materialsavailable from PPG Industries, Inc.

The nickel-free zinc phosphate pretreatment bath was adjusted to a freeacid value of 0.8-1.0 mL with Buffer M. The free acid value was measuredby titrating a 10 mL sample of the bath with 0.1 N sodium hydroxidesolution, using bromophenol blue as an indicator and titrating to ablue-gray endpoint.

Example 1

Four hot dipped galvanized panels (4 inches×6 inches, automotive-gradematerial from Salzgitter Mannesmann Stahlservice GmbH) and four coldrolled steel panels (4.13 inches×6 inches, standard test panels fromChemetall GmbH) were spray cleaned with a mixture of Chemkleen 2010LP(1.25% v/v)/Chemkleen 181ALP (0.125% v/v) for 2 minutes at 49° C.followed by immersion rinse in DI water for 15 seconds and spray rinsewith DI water for 15 seconds. Panels were then immersed in a bath (20°C.-25° C.) containing the MMM activating rinse (either with or withoutmetal sulfate, pre-dissolved in a minimal amount of DI water beforebeing added to the MMM activating rinse, as shown in Table 1) for 1minute. All panels were then immersed in the nickel-free zinc phosphatepretreatment bath (50° C.) for 3 minutes. Panels then were spray rinsedwith DI water for 20-30 seconds. Panels were warm air dried using aHi-Velocity handheld blow-dryer made by Oster® (model number078302-300-000) on high-setting at a temperature of about 50-55° C.until the panel was dry (about 1-5 minutes).

For each run, one panel was used to determine phosphate coatingcompleteness. The other panel was cut in half to yield two panels each2″×3″ and one of the half panels was used to determine coating weightand the other half panel was used to determine average crystal size.

Zinc phosphate coating weight was determined on one of the 2″×3″ panelsby the weigh-strip-weigh method. Treated panels were weighed on ananalytical balance to the nearest 0.1 mg. Cold roll steel panels wereimmersed in a solution comprised of 100 g sodium hydroxide pellets and25 milliliters 98% triethanolamine diluted to 1 liter total volume withdeionized water for 1.5 minutes to dissolve all of the zinc phosphatecoating off of the panels without dissolution of the substrate. Hotdipped galvanized steel panels were immersed in a solution comprised of16 g ammonium dichromate [(NH₄)₂Cr₂O₇] dissolved into 1 literconcentrated ammonium hydroxide for 2 minutes to dissolve all of thezinc phosphate coating off of the panels without dissolution of thesubstrate. After the stripping procedure, panels were rinsed thoroughlywith deionized water, wiped gently with a tissue to remove anyloosely-adherent phosphate coating, rinsed with deionized water again,and dried in warm air by using a Hi-Velocity handheld blow-dryer made byOster® (model number 078302-300-000) on high-setting at a temperature ofabout 50-55° C. until the panel was dry, typically 1-5 minutes. Thedried panel was then weighed, and the weight loss was used to calculatethe coating weight per unit area.

Zinc phosphate average crystal size was determined on 2″×3″ panels byfirst selecting a representative area of the panel, i.e., a coated areaof approximately 0.5 inch by 0.5 inch near the center of the 2″×3″ panelwith no obvious coating defects, then acquiring an image at either5,000× or 10,000× magnification using a Tescan Vega 2 scanning electronmicroscope (SEM). The magnification was determined by the crystal sizewith the 10,000× magnification required for smaller crystal sizes. Nineto twelve evenly-spaced crystals on each image were measured usingImageJ software (version 1.46), and the results averaged. ImageJsoftware is public domain software, available fromhttp://imagej.nih.gov/ij/. Further details of the method have alreadybeen described above.

Following pretreatment, for each run, two panels of the treated panelsthen were electrocoated using Enviroprime NT, a cathodic electrocoatavailable from PPG Industries, Inc. and applied according to themanufacturer's instructions. The electrodeposition was carried out at220 volts, using a 30 second ramp. The electrodeposition bathtemperature was 90° F. The current density was 1.5 A/ft² and the panelswere coated to 27 Coulombs to reach a dry film thickness of 18-20 μm.

The electrocoated panels were tested for paint adhesion (dry adhesionand exposed adhesion, described in more detail below) by crosshatchingand tape-pulling. For the dry adhesion test, a razor blade was used toscribe eleven lines parallel and perpendicular to the length of the oneof the electrocoated panels. The resultant grid area of the scribedlines was 0.5″×0.5″ to 0.75″ to 0.75″ square. Dry adhesion was assessedby using 3M's Scotch 610 tape, which was firmly adhered over the scribedgrid area by finger rubbing it multiple times prior to pulling it off.The crosshatch area was evaluated for paint loss on a scale from 0 to10, with 0 being total paint loss and 10 being absolutely no paint loss.An adhesion value of 7 is considered acceptable in the automotiveindustry. For the exposed adhesion test, following electrodeposition,the other panel was immersed in deionized water (40° C.) for ten days,at which time the panels were removed, wiped with a towel to dry andallowed to sit at ambient temperature for one hour prior tocrosshatching and tape-pulling to evaluate paint adhesion as describedabove.

Metal phosphate coating weight (g/m²), metal phosphate crystal size, anddry and exposed adhesion performance for the treated panels are reportedin Table 1, below.

TABLE 1 Coating Crystal Activating Weight Size Dry Exposed Rinse MetalSulfate (g/m²) (μm) Adhesion Adhesion Hot Dipped Galvanized MMM None 4.01.8 10 0 (Compar- ative) MMM Zinc Sulfate 3.7 1.8 9 0 (66 ppm zinc, 100ppm sulfate) MMM Nickel Sulfate 2.1 1.0 9 9 (61 ppm nickel, 100 ppmsulfate) MMM Cobalt Sulfate 2.1 0.9 9 9 (62 ppm cobalt, 100 ppm sulfate)Cold Rolled Steel MMM None 0.9 3.1 10 10 (Compar- ative) MMM ZincSulfate 0.8 2.2 10 10 (66 ppm zinc, 100 ppm sulfate) MMM Nickel Sulfate0.8 2.4 10 10 (61 ppm nickel, 100 ppm sulfate) MMM Cobalt Sulfate — 2.310 10 (62 ppm cobalt, 100 ppm sulfate)

As shown in Table 1, immersion of hot dipped galvanized steel panels inactivating baths made from MMM activating rinse compositions that didnot include a metal sulfate or that included zinc sulfate had an exposedadhesion value of zero, indicating extremely poor adhesion. In contrast,when panels were immersed in activating baths made from activating rinsecompositions that included either nickel sulfate or cobalt sulfate,exposed adhesion performance was significantly improved to a rating of9. As stated above, an adhesion value of at least 7 is consideredacceptable in the automotive industry. Inclusion of nickel sulfate orcobalt sulfate in the activating rinse composition also resulted in adecreased coating weight and decreased crystal size.

Example 2

For each run shown in Table 2, four “North American” hot dippedgalvanized (HDG) panels (4 inches×6 inches, from ACT Test Panels) andfour “European” HDG panels (4.13 inches×6 inches, from Chemetall GmbH)were spray cleaned with a mixture of Chemkleen 2010LP (1.25%v/v)/Chemkleen 181ALP (0.125% v/v) for 2 minutes at 49° C. followed byimmersion rinse in DI water for 15 seconds and spray rinse with DI waterfor 15 seconds. Panels were then immersed in a bath (20° C.-25° C.)containing either the RC, RC30, or MMM activating rinse (either with orwithout metal sulfate, as shown in Table 1) for 1 minute. Panels werethen immersed in either a nickel-free zinc phosphate pretreatment bath(30° C. or 50° C.) for 3 minutes or a nickel-containing zinc phosphatepretreatment bath (50° C.) for 3 minutes. Panels then were spray rinsedwith DI water for 20-30 seconds. Panels were warm air dried using aHi-Velocity handheld blow-dryer made by Oster® (model number078302-300-000) on high-setting at a temperature of about 50-55° C.until the panel was dry (about 1-5 minutes).

Coating weight and average zinc phosphate crystal size was measured asdescribed in Example 1.

Two panels were electrocoated using Enviroprime NT, a cathodicelectrocoat available from PPG Industries, Inc. using the same processdescribed in Example 1. One panel was then tested by the dry adhesiontest and the other panel was tested by the exposed adhesion test, asdescribed in Example 1.

Coating weight (g/m²), crystal size, and dry and exposed adhesionperformance for the treated North American HDG panels are reported inTable 2 and for the treated European HDG panels are reported in Table 3.

The results in Tables 2 and 3 show that the inclusion of nickel sulfateor cobalt sulfate in RC30 or MMM activating rinse results in reducedcrystal size and coating weight of a subsequently applied nickel-freezinc phosphate coating compared to the use of activating rinses that donot include nickel sulfate or cobalt sulfate. Table 2 further shows thatthe inclusion of nickel sulfate or cobalt sulfate in an activating rinsegenerally improves the dry and exposed adhesion of a subsequentlyapplied electrodepositable coating over the phosphate coating, even whenthe zinc phosphate pretreatment composition was applied atlow-temperatures.

Example 3

Comparative Example I was made according to Example 2 of US Publication2012/0160129A1 to Inbe. RC and Composition 2A were made as describedabove.

The dispersion of Comparative I was characterized as follows and wascompared to the activation properties of Composition 2A.

X-ray diffraction of dried solids of Comparative I showed both ZnO andzinc phosphate.

Particle size (D₁₀, D₅₀, and D₉₀) were measured using a Mastersizer 2000(available from Malvern Instruments, Ltd., of Malvern, Worcestershire,UK). A laser beam (0.633 mm diameter, 633 nm wavelength) was directedthrough a dispersion of particles (in deionized water to 2-3%obscuration). The light scattering of the dispersion was measured(measurement parameters 25° C., 2200 RPM, 30 sec premeasurement delay,10 sec background measurement, 10 sec sample measurement) and the datawere analyzed by computer software (Malvern Mastersizer 2000 software,version 5.60) to generate a particle size distribution, from whichparticle sizes (mean, D₁₀, D₅₀, and D₉₀) were determined and arereported in Table 4.

TABLE 4 Mean PS D10 D50 D90 Sample (μ) (μ) (μ) (μ) Composition I(Initial) 3.914 1.528 3.495 6.904 Composition I (60 min) 0.643 0.1250.456 1.31 Composition I (120 min) 0.493 0.109 0.338 0.985 Composition I(180 min) 0.474 0.096 0.284 0.917 Composition 2A 0.181 0.068 0.119 0.332Composition RC30 0.846 0.079 0.215 2.75

For each run shown in Table 5, cold rolled steel, electrogalvanizedsteel, or aluminum alloy 6022 panels (4″×6″, all available from ACT TestPanels, LLC) were spray cleaned with a mixture of Chemkleen 2010LP(1.25% v/v)/Chemkleen 181ALP (0.125% v/v) for 2 minutes at 49° C./120Ffollowed by immersion rinse in DI water for 15 seconds and spray rinsewith DI water for 15 seconds. Panels were then immersed in a bath (20°C.-25° C.) containing either Comparative Example I or Composition 2A, asshown in Table 5, for 1 minute. Activated panels (Comparative Example Ior Composition 2A) then were immersed in a zinc phosphate pretreatmentbath (made from Chemfos 700AL, commercially available from PPGIndustries, Inc., prepared according to instructions provided by thesupplier) at a bath temperature of either 78F for 2 minutes. All panelsthen were spray rinsed with DI water for 20-30 seconds. Panels were warmair dried using a Hi-Velocity handheld blow-dryer made by Oster® (modelnumber 078302-300-000) on high-setting at a temperature of about 50-55°C. until the panel was dry (about 1-5 minutes).

For each run, one of the panels was used to determine phosphate coatingcompleteness. The other panel was cut in half to yield two panels each2″×3″ and one of the half panels was used to determine coating weightand the other half panel was used to determine average crystal size.

Zinc phosphate coating completeness and coating weight were determinedas described in Example 1. Zinc phosphate average crystal size wasdetermined as described in Example 1. Data are reported in Table 5,below.

TABLE 5 Coating Crystal Coating Complete- size weight SubstrateActivator ness (μm) (mg/ft²) Cold rolled steel Composition 2A 100% 1.2094 Cold rolled steel Comparative I  60% 2.88 153 Electrogalvanized steelComposition 2A 100% 1.22 289 Electrogalvanized steel Comparative I 100%3.00 359 Aluminum alloy 6022 Composition 2A  95% 1.45 142 Aluminum alloy6022 Comparative I  40% 3.05 153

As shown in Table 5, Composition 2A gave 100% coating completeness onCRS and 95% coating completeness on aluminum alloy 6022 panels. Incontrast, Comparative I gave only 60% coating completeness on CRS and40% coating completeness on aluminum alloy 6022 panels. Both Composition2A and Comparative I gave 100% coating completeness on EG steel panels,but the skilled artisan understands that EG panels are typically 100%coated. Also as shown in Table 5, Additionally, crystal size was smallerand coating weight was lower on panels treated with Composition 2A thanthose treated with Comparative I, regardless of substrate.

It will be appreciated by skilled artisans that numerous modificationsand variations are possible in light of the above disclosure withoutdeparting from the broad inventive concepts described and exemplifiedherein. Accordingly, it is therefore to be understood that the foregoingdisclosure is merely illustrative of various exemplary aspects of thisapplication and that numerous modifications and variations can bereadily made by skilled artisans which are within the spirit and scopeof this application and the accompanying claims.

ASPECTS OF THE INVENTION

-   1. A substrate pretreatment system, comprising:    -   a) an activating rinse for treating at least a portion of a        substrate comprising a dispersion of metal phosphate particles        having a D₉₀ particle size of no greater than 10 μm, wherein the        metal phosphate comprises divalent or trivalent metals or        combinations thereof; and    -   b) a pretreatment composition for treating at least a portion of        the substrate treated with the activating rinse, comprising zinc        ions and phosphate ions, wherein the pretreatment composition is        substantially free of nickel.-   2. The pretreatment system of Aspect 1, wherein the D₉₀ particle    size is measured from a sample of the activating rinse that has been    sonicated.-   3. The pretreatment system of Aspect 1 or 2, wherein the activating    rinse further comprises a metal sulfate salt, wherein the sulfate of    the metal sulfate salt is present in an amount of 5 ppm to 5000 ppm    based on a total weight of the activating rinse.-   4. The pretreatment system of any of the preceding Aspects, wherein    the metal phosphate particles have a D₉₀ particle size of no more    than 1 μm, preferably of 50 nm to 500 nm.-   5. The pretreatment system of any of the preceding Aspects, wherein    the divalent or trivalent metals of the metal phosphate in the    activating rinse comprise zinc, iron or a combination thereof.-   6. The pretreatment system of any of the preceding Aspects, wherein    the activating rinse comprises a dispersant comprising non-ionic    polymers.-   7. The pretreatment system of any of the preceding Aspects, wherein    the activating rinse is substantially free of ionic dispersants.-   8. The pretreatment system of any of the preceding Aspects, wherein    the metal of the metal sulfate salt comprises nickel, copper, zinc,    iron, magnesium, cobalt, aluminum or combinations thereof,    preferably nickel, cobalt or combinations thereof.-   9. A method of treating a substrate comprising:    -   a) contacting at least a portion of a surface of the substrate        with an activating rinse comprising a dispersion of metal        phosphate particles having a D₉₀ particle size of no greater        than 10 μm, wherein the metal phosphate comprises divalent or        trivalent metals or combinations thereof; and    -   b) contacting at least a portion of the surface that has been        contacted with the activating rinse with a pretreatment        composition comprising zinc ions and phosphate ions, wherein the        pretreatment composition is substantially free of nickel.-   10. The method of Aspect 9, wherein the D₉₀ particle size is    measured from a sample of the activating rinse that has been    sonicated.-   11. The method of Aspect 9 or 10, wherein the contacting with the    pretreatment composition comprises immersing the substrate in a bath    comprising pretreatment composition, wherein the bath temperature is    20° C. to 60° C.-   12. The method of Aspects 9 to 11, wherein the activating rinse    further comprises a metal sulfate salt, wherein the metal of the    metal sulfate salt comprises nickel, copper, zinc, iron, magnesium,    cobalt, aluminum or combinations thereof, preferably nickel, cobalt    or combinations thereof.-   13. The method of any of Aspects 9 to 12, wherein the substrate is    treated with the substrate pretreatment system according to any of    Aspects 1 to 8.-   14. A substrate treated with the pretreatment system of any of    Aspects 1 to 8, preferably in a method according to any of Aspects 9    to 13.-   15. The substrate of Aspect 13, wherein the phosphate coating formed    from the pretreatment composition comprises metal/zinc phosphate    crystals having an average crystal size of 0.4 μm to 2 μm,    preferably of 0.7 μm to 1.5 μm as measured by a scanning electron    microscope at 10,000× magnification.-   16. The substrate of Aspects 14 or 15, wherein the phosphate coating    has a weight of 4.4 g/m² or less and an exposed adhesion value of 6    or greater.-   17. The substrate of any of Aspects 14 to 16, wherein the phosphate    coating has a weight of 0.5 to 4 g/m² as measured by the    weigh-strip-weigh method.-   18. The substrate of any of Aspects 14 to 17, wherein the    pretreatment composition has been applied from a pretreatment bath    having a temperature of 20° C. to 60° C.-   19. The substrate of any of Aspects 14 to 18, wherein the substrate    further comprises an electrodeposited layer.

1. A substrate pretreatment system, comprising: a) an activating rinsefor treating at least a portion of a substrate comprising a dispersionof metal phosphate particles having a D90 particle size of no greaterthan 10 □m, wherein the metal phosphate comprises divalent or trivalentmetals or combinations thereof; and b) a pretreatment composition fortreating at least a portion of the substrate treated with the activatingrinse, comprising zinc ions and phosphate ions, wherein the pretreatmentcomposition is substantially free of nickel.
 2. The pretreatment systemof claim 1, wherein the activating rinse further comprises a metalsulfate salt, wherein the sulfate of the metal sulfate salt is presentin an amount of 5 ppm to 5000 ppm based on a total weight of theactivating rinse.
 3. The pretreatment system of claim 1, wherein the D₉₀particle size is measured from a sample of the activating rinse that hasbeen sonicated.
 4. The pretreatment system of claim 1, wherein the metalphosphate particles have a D₉₀ particle size of no more than 1 μm. 5.The pretreatment system of claim 4, wherein the D₉₀ particle size ismeasured from a sample of the activating rinse that has been sonicated.6. The pretreatment system of claim 1, wherein the metal phosphateparticles have a D₉₀ particle size of 50 nm to 500 nm.
 7. Thepretreatment system of claim 1, wherein the divalent or trivalent metalsof the metal phosphate in the activating rinse comprise zinc, iron or acombination thereof.
 8. The pretreatment system of claim 1, wherein thepretreatment composition is used in a pretreatment bath having atemperature of 20° C. to 60° C.
 9. The pretreatment system of claim 1,wherein the metal of the metal sulfate salt comprises nickel, copper,zinc, iron, magnesium, cobalt, aluminum or combinations thereof.
 10. Thepretreatment system of claim 1, wherein the metal of the metal sulfatesalt comprises nickel, cobalt or combinations thereof.
 11. A substratetreated with the pretreatment system of claim
 1. 12. The substrate ofclaim 11, wherein the phosphate coating formed from the pretreatmentcomposition comprises metal/zinc phosphate crystals having an averagecrystal size of 0.4 μm to 2 μm as measured by a scanning electronmicroscope at 10,000× magnification.
 13. The substrate of claim 11,wherein the phosphate coating formed from the pretreatment compositioncomprises metal/zinc crystals having an average crystal size of 0.7 μmto 1.5 μm as measured by a scanning electron microscope at 10,000×magnification.
 14. The substrate of claim 11, wherein the phosphatecoating has a weight of 0.5 to 4 g/m² as measured by theweigh-strip-weigh method.
 15. The substrate of claim 11, wherein thephosphate coating has a weight of 4.4 g/m² or less and an exposedadhesion value of 6 or greater.
 16. The substrate of claim 11, whereinthe D₉₀ particle size is measured from a sample of the activating rinsethat has been sonicated.
 17. The substrate of claim 11, furthercomprising an electrodeposited layer.
 18. A method of treating asubstrate comprising: a) contacting at least a portion of a surface ofthe substrate with an activating rinse comprising a dispersion of metalphosphate particles having a D₉₀ particle size of no greater than 10 μm,wherein the metal phosphate comprises divalent or trivalent metals orcombinations thereof; and b) contacting at least a portion of thesurface that has been contacted with the activating rinse with apretreatment composition comprising zinc ions and phosphate ions,wherein the pretreatment composition is substantially free of nickel.19. The method of claim 18, wherein the (b) contacting comprisesimmersing the substrate in a bath comprising the pretreatmentcomposition, wherein the bath temperature is 20° C. to 60° C.
 20. Themethod of claim 18, wherein the metal of the metal sulfate saltcomprises nickel, copper, zinc, iron, magnesium, cobalt, aluminum orcombinations thereof.
 21. The method of claim 18, wherein the metal ofthe metal sulfate salt comprises nickel, cobalt or combinations thereof.22. The method of claim 18, wherein the activating rinse furthercomprises a metal sulfate salt.
 23. The substrate of claim 18, whereinthe D₉₀ particle size is measured from a sample of the activating rinsethat has been sonicated.